Modeling of Disperse Multiphase Flows

摘要CTS-9521374 多相流的工程描述必须建立在宏观方程的基础上，在宏观方程中，相的不均匀性是平均的，而不是详细的。 在制定模型的困难在于这样一个事实，即任何平均程序适用于连续介质力学的基本方程导致模型包含更多的未知数比方程。 因此，基本问题是封闭方程组，即确定用其他变量表示某些未知量的“本构关系”。 这是分散流的情况下，如在流体相的颗粒拟议的研究的中心主题。 这个问题将攻击依赖于一个新的方法来推导平均方程和国家的最先进的数值直接模拟技术。 这两个工具以前都是在NSF的支持下开发的。 新的平均程序表示未知的粒子表面上的积分，可以很容易地从运动的数值模拟计算。 计算将通过在大规模并行超级计算机上实施的时空有限元方法进行。 对方程结构的洞察，如果成功的话，将从这项研究中得到承诺，回答长期存在的问题，如方程的数学结构及其与观察现象的关系。 进行这项研究所需的数值技术的增强本身就构成了当前直接数值模拟能力的一个重大进步。 这项研究将与明尼苏达大学（双子城）的Tayfun Tezduyar教授一起进行，他从NSF获得了单独的资助。 ***

ABSTRACT CTS-9521374 An Engineering description of multi-phase flows by necessity must be made on the basis of macroscopic equations in which the phase inhomogeneties are accounted for in an average sense, rather than in detail. The difficulty in formulating the models resides in the fact that any averaging procedure applied to the fundamental equations of continuum mechanics leads to models containing more unknowns than equations. The fundamental problem is then that of closing the equation set, namely of determining "constitutive relations" that express some unknown quantities in terms of others. This is the central theme of the proposed research for the case of disperse flows, such as particles in a fluid phase. The problem will be attacked by relying on a new method for deriving averaged equations and on the state-of-the-art numerical direct-simulation techniques. Both tools have been previously developed under NSF support. The new averaging procedure expresses the unknown in terms of integrals over the particles surfaces that can readily be calculated from numerical simulations of the motion. The computations will be carried out by means of a space-time finite-element method implemented on massively parallel supercomputers. The insight into the structure of the equations that, if successful, will derive from this research promises to answer long-standing questions as to the mathematical structure of the equations and their relationship to observe phenomena. The enhancement of the numerical techniques necessary to carry out this research constitutes in itself a significant advancement in the current direct numerical simulation capabilities. This research will be carried out in conduction with Professor Tayfun Tezduyar of the University of Minnesota (Twin Cities) who has a separate grant from NSF. ***